NAME

       truncate - truncate a file to a specified length

SYNOPSIS

       #include <unistd.h>

       int truncate(const char *path, off_t length);

DESCRIPTION

       The  truncate()  function  shall cause the regular file named by path to have a size which
       shall be equal to length bytes.

       If the file previously was larger than length, the extra data is discarded.  If  the  file
       was  previously  shorter than length, its size is increased, and the extended area appears
       as if it were zero-filled.

       The application shall ensure that the process has write permission for the file.

       If the request would cause the file size to exceed  the  soft  file  size  limit  for  the
       process,  the  request shall fail and the implementation shall generate the SIGXFSZ signal
       for the process.

       This function shall not modify the file offset for any open file  descriptions  associated
       with  the  file.  Upon  successful  completion, if the file size is changed, this function
       shall mark for update the st_ctime and st_mtime fields of the file, and  the  S_ISUID  and
       S_ISGID bits of the file mode may be cleared.

RETURN VALUE

       Upon  successful  completion,  truncate() shall return 0. Otherwise, -1 shall be returned,
       and errno set to indicate the error.

ERRORS

       The truncate() function shall fail if:

       EINTR  A signal was caught during execution.

       EINVAL The length argument was less than 0.

       EFBIG or EINVAL
              The length argument was greater than the maximum file size.

       EIO    An I/O error occurred while reading from or writing to a file system.

       EACCES A component of the path prefix denies search permission,  or  write  permission  is
              denied on the file.

       EISDIR The named file is a directory.

       ELOOP  A loop exists in symbolic links encountered during resolution of the path argument.

       ENAMETOOLONG
              The  length  of  the  path  argument  exceeds {PATH_MAX} or a pathname component is
              longer than {NAME_MAX}.

       ENOENT A component of path does not name an existing file or path is an empty string.

       ENOTDIR
              A component of the path prefix of path is not a directory.

       EROFS  The named file resides on a read-only file system.

       The truncate() function may fail if:

       ELOOP  More than {SYMLOOP_MAX} symbolic links were encountered during  resolution  of  the
              path argument.

       ENAMETOOLONG
              Pathname resolution of a symbolic link produced an intermediate result whose length
              exceeds {PATH_MAX}.

       The following sections are informative.

EXAMPLES

       None.

APPLICATION USAGE

       None.

RATIONALE

       None.

FUTURE DIRECTIONS

       None.

SEE ALSO

       open() , the Base Definitions volume of IEEE Std 1003.1-2001, <unistd.h>

COPYRIGHT

       Portions of this text are reprinted and  reproduced  in  electronic  form  from  IEEE  Std
       1003.1,  2003  Edition,  Standard  for Information Technology -- Portable Operating System
       Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003  by
       the  Institute  of  Electrical  and  Electronics Engineers, Inc and The Open Group. In the
       event of any discrepancy between this version and the original IEEE  and  The  Open  Group
       Standard,  the  original  IEEE  and  The  Open Group Standard is the referee document. The
       original Standard can be obtained online at http://www.opengroup.org/unix/online.html .